Glen Tapia got cut Saturday night for the first time in his four-year pro career.

The undefeated junior-middleweight prospect also went the distance against Dashon Johnson in an eight-round fight TV Azteca didn’t air as planned. The 22-year-old Tapia realized, though, that his 16th professional fight still served its purpose in El Paso, Texas.

After recording four straight knockouts, mostly against overmatched opposition, the Passaic, N.J., native got in some much-needed rounds against Johnson (13-8-3, 4 KOs), who has been stopped just once in 24 fights.

“It was a tough fight,” Tapia told BoxingScene.com. “He was s durable buy. He came to fight and I gave the fans a good show. They were happy with the fight. But this makes me want to work harder. It makes me want to not even get a little tired during a fight. I’m actually real happy this happened, that I went eight rounds. It was a good learning experience for me.”

Tapia (16-0, 9 KOs), who’s co-promoted by Bob Arum’s Top Rank Inc. and New Jersey-based Pound-For-Pound Promotions, hurt Johnson toward the end of the fourth round. Johnson withstood the trouble and finished the fight on his feet.

Two rounds earlier, an accidental clash of heads opened a cut near the left side of Tapia’s hairline.

He needed several stitches to close the wound, but Tapia said his first cut didn’t affect him during the fight. Tapia also doesn’t think the laceration will keep him out of action for too long.

Matchmakers for Top Rank want Manny Pacquiao’s former sparring partner to compete in at least two more eight-round fights before advancing him to 10-rounders sometime in 2013. His handlers intend to increase the level of Tapia’s opposition in his next fight as well.

He was supposed to box Juan De La Rosa (20-3-1, 15 KOs), of Harlingen, Texas, on Saturday night at El Paso County Coliseum. De La Rosa, of “The Contender” fame, withdrew from the fight for undisclosed medical reasons 2½ weeks ago.

Johnson, of Escondido, Calif., took the fight on short notice, despite that he lost a six-round decision unanimous to prospect Daquan Arnett (8-0, 5 KOs) just two weeks ago in Juncos, Puerto Rico. The 24-year-old journeyman lost to Tapia by wide margins on all three scorecards (79-73, 79-73, 78-74), just as he did against Arnett (60-54, 60-54, 59-55).

“I’m never happy with my fights,” said Tapia, who went eight rounds for the first time. “I’m my worst critic. I’m happy with the lesson that it gave me, but I’m not 100-percent happy with my performance.”

Keith Idec covers boxing for The Record and Herald News, of Woodland Park, N.J., and BoxingScene.com. He can be reached on Twitter @Idecboxing.